Fe3O4 and Au nanoparticles dispersed on the graphene support as a highly active catalyst toward the reduction of 4-nitrophenol.

We report a highly efficient and reusable bifunctional nanostructured composite catalyst synthesized by a scalable facile hydrothermal method which enables the precise control of size and morphology of nanoparticles, wherein Au nanoparticles (NPs) and Fe3O4 particles exhibit excellent dispersing ability on the rGO (reduced graphene oxide) sheet surface (designated as rGO/Fe3O4/Au) to avoid adverse agglomeration between the nano particles and overlapping of the rGO sheets concurrently. The resultant bifunctional composite shows a high performance in the catalytic reduction of 4-nitrophenol (4-NP) with a conversion of 97% in 5 min and presents good reusability through highly efficient recovery by using external magnetic fields. In particular, there was no significant loss in catalytic activity of the reused catalysts even after being recycled for 8 cycles, displaying attractive potential in industrial applications where separation and recycling are imperative. The rational design provides an approach to synthesize a graphene-based composite with an interesting structure and multi-functional properties as well.